So that’s made the exercise of writing a “delightfully short” guide to social media ROI all the more fun and challenging. I’ve given myself under1,000words to provide an overview of social media ROI and how to apply it to yoursocial media marketing efforts. I’d love to hear your feedback in the comments!

What DoesSocial Media ROI Look Like?

ROI has its roots in business finance. Businesses use ROI to calculate the dollars-and-cents return on a dollars-and-cents investment.

Social media ROI is what you get back from all the time, effort, and resources you commit to social.
And it’s best calculated with dollar amounts.

Social media ROI is what you get back from all the time, effort, and resources you commit to social.

Of course, there are no dollar signs dangling from retweets or likes. Twitter, Facebook, and others are no-costmarketing channels to join, potentiallya zero-dollar investment (which makes any return exponentially fantastic, right!).

Discussion
. This study shows that, in ~50% of immunocompetent children with nontuberculous mycobacterial cervical lymphadenitis, the indurative reaction to
M. tuberculosis
PPD measures ⩽15 mm by the ball-pen method, and in ~25%, it measures <10 mm. Although large indurations have been found among adults infected with various nontuberculous mycobacterial species [
4
], the incidence of large indurations found here is greater than that reported elsewhere in series of children with cervical lymphadenitis. Wolinsky [
5
] reviewed results of 105 American children with presumed nontuberculous mycobacterial lymphadenitis (83 culture-proven cases), of whom 91 underwent a PPD skin test; only 7 children (8%) showed indurations of >15 mm, whereas 57 (63%) had indurations of ⩾10 mm. In another study from Greece, among 43 of 47 pediatric inpatients with presumed nontuberculous mycobacterial lymphadenitis (40 culture-proven cases) who underwent a tuberculin test, the median induration was 7 mm (range, 0–15 mm), and most patients (70%) had indurations of <10 mm [
6
].

Discussion

Differences between our results and those from different parts of the world [
5
,
6
] may indicate the existence of different nontuberculous mycobacterial species and subspecies. This diversity may result from regional environmental factors that affect mycobacterial cell wall structure and, consequently, immunogenicity.

In fact, in contrast to previous reports among children with nontuberculous mycobacterial lymphadenitis [
5–7
], we had a high isolation rate of
M. haemophilum.
This might be the result of a high prevalence of this species in our geographic area, but it may also be attributable to our laboratory routine of use of broth with an iron supplement incubated at 30°C for processing aspirated specimens [
3
]. Correa and Starke [
8
] claimed that the size of reactions to
M. tuberculosis
PPD in infections caused by
M. avium-intracellulare
complex is usually 0–10 mm and rarely exceeds 18 mm, whereas infections caused by other species, especially
Mycobacterium marinum
and
Mycobacterium fortuitum
, are frequently associated with reactions of 10–20 mm. Because of scant data, it is impossible to estimate the range of indurative responses to
M. tuberculosis
PPD in children infected with
M. haemophilum
in other parts of the world. Nevertheless, our series shows that this species can occasionally be very immunogenic.